A regulatory body having a jurisdiction over classes of mobile communication systems imposes the requirement of an emergency service. For instance the Federal Communications Commission's (FCC's) orders docket 94-102 for Wireless E911 service, an exemplary emergency service, both in spirit and by order, intends that wireless subscribers, with a high probability of success, can:                Perform timely call completions for emergency calls;        Initiate emergency calls on any available wireless system;        Receive emergency callback service for a specific time duration, once the emergency call serving network is aware of the subscribers callback number; and        Be provided with clear notification of outgoing emergency calls.        
Although regulatory bodies differ in jurisdiction and class of mobile communication systems, all communication systems would benefit from the enhanced probability of successfully completing a call to emergency services.